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  • Chemistry  (13)
  • molten globule state of proteins  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Compact state of a protein molecule with pronounced small-scale mobility: bovine α-lactalbumin (1985)
    Springer
    European biophysics journal 13 (1985), S. 109-121 
    Details
    ISSN: 1432-1017
    Keywords: Protein denaturation ; protein folding, α-lactalbumin ; molten globule state of proteins ; phase transitions in proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract We describe a novel physical state of a protein molecule which is nearly as compact as the native state and has pronounced secondary structure, but differs from the native state by the large increase of thermal fluctuations (in particular, by the large mobility of side groups). This state has been characterized in detail for the acid form of bovine α-lactalbumin as a result of the study of physical properties of this state by a large variety of different methods (hydrodynamics, diffuse X-ray scattering, circular dichroism and infrared spectra, polarization of the luminescence, proton magnetic resonance, deuterium exchange and microcalorimetry). It has been shown that bovine α-lactalbumin can be transformed into a similar state by thermal denaturation. This process is thermodynamically two state (i.e. all-or-none transition), which means that this state differs from the native one by a phase transition of the first order.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00256531
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  • 2
    Electronic Resource
    Electronic Resource
    Thermodynamic parameters of helix-coil transition in polypeptide chains. II. Poly-L-lysine (1971)
    New York : Wiley-Blackwell
    Biopolymers 10 (1971), S. 2181-2197 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The helix-coil transitions for poly-L-lysine (PL) were investigated by the methods of spectropolarimetry, viscometry and potentiometric titration in 0.2M NaCl at different temperatures as well as in 0.2MNaBr, 1MKCl, and in mixtures of 0.2MNaCl or NaBr with methanol at room temperature. The enthalpy and entropy differences between the helical and coillike states of uncharged PL molecules in 0.2.M NaCl were determined from the potentiometric titration curves. The cooperativity parameters σ for PL in different solvents were determined by two methods (from the sharpness of the transition and from the dependence of the intrinsic viscosity on the helical content in the transition region). In 0.2MNaCl σ has a value of (2.3 ± 0.5) × 10-4 and does not depend on temperature, i.e., the cooperativity of the helix-coil transition, as for PGA, is mainly of an entropy origin (the initiating of the helical region is accompanied by the entropy decrease ΔSi = -12 eu/mole of helical regions). A comparison of the obtained results for PGA and PL with the molecular theories of the helix-coil transitions shows that the role of dipole-dipole interactions of nonneighboring peptide groups is greatly overestimated in these theories, leading to a considerable enthalpy contribution to the free energy of initiating helical regions which is not observed in the experiment.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360101112
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  • 3
    Electronic Resource
    Electronic Resource
    Theory of protein molecule self-organization. I. Thermodynamic parameters of local secondary structures in the unfolded protein chain (1977)
    New York : Wiley-Blackwell
    Biopolymers 16 (1977), S. 469-495 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: This paper presents the results of a stereochemical analysis of local interactions in unfolded protein chains (sterical repulsions, hydrogen, and hydrophobic bonds, etc.) by means of space-filling modeles. On the basis of this analysis, an evaluation is made of thermodynamic parameters controlling the building-in of all the 20 natural amino acid residues in all the physically possible position of local secondary structures (α-helices, including α-helices with short fragments of helices 310 at the C-terminus; β-bends of different types, helices 310, and their combinations) as well as thermodynamic parameters of separate hydrogen bonds of polar side groups with the neighbor peptide groups (“local contacts”). The accuracy of the obtained results is discussed.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1977.360160302
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  • 4
    Electronic Resource
    Electronic Resource
    Theory of protein secondary structure and algorithm of its prediction (1983)
    New York : Wiley-Blackwell
    Biopolymers 22 (1983), S. 15-25 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A molecular theory of protein secondary structure is presented that takes account of both local interactions inside each chain region and long-range interactions between different regions, incorporating all these interactions in a single Ising-like model. Local interactions are evaluated from the stereochemical theory describing the relative stabilities of α- and β-structures for different residues in synthetic polypeptides, while long-range effects are approximated by the interaction of each chain region with the averaged hydrophobic template. Based on this theory, an algorithm of protein secondary structure prediction is proposed and examples are given of “blind” predictions made before the x-ray structural data became available.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360220105
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  • 5
    Electronic Resource
    Electronic Resource
    Method of determining the relative stability of different conformational states of biological macromolecules (1969)
    New York : Wiley-Blackwell
    Biopolymers 7 (1969), S. 435-445 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general approach to the determination of relative stability of any pair of con-formational states of biological macromolecules or their complexes (in particular, to the determination of relative stability of native and disordered states of the macromolecule) has been suggested. For determining the free energy difference of the two states under the conditions when one of them is considerably more advantageous than the other, it is necessary for the macromolecule to be influenced by the transforming agent which levels free energies of both the conformational states, and to determine the external parameter derivative of the free energy difference in the region of the conformational transition induced by the change in this parameter. If the character of the dependence of this derivative on the external parameter (temperature, solvent composition, etc.) is known, then this allows the determination of the free energy difference of the two states under the conditions considered, even including conditions far from the transition region. The value of the derivative of the free energy difference in the transition region in many cases can be measured directly (in particular, when using calorimetry), while in cases when a direct measurement of the derivative is impossible, it can often he estimated experimentally from the steepness of the conformational transition. The methods of this estimation and also a possible character of the change of the considered derivative during variation of the external parameter are considered for the case when the transforming agent is one of the components of the solvent and, consequently, the derivative of the free energy difference is equal to the difference of number of molecules of this component hound with the macromolecule in two conformational states.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1969.360070402
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  • 6
    Electronic Resource
    Electronic Resource
    Noncooperative temperature melting of a globular protein without specific tertiary structure: Acid form of bovine carbonic anhydrase B (1985)
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 1899-1907 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heat denaturation of native globular proteins is a cooperative process usually connected with the melting of the main part of their regular secondary structure. In this paper, a noncooperative temperature-induced melting of the regular secondary structure in the carbonic anhydrase B at pH 2.6 in heavy water is observed by ir spectroscopy. The molecules of carbonic anhydrase B in an acid medium, unlike the native ones, do not have a specific tertiary structure. Nevertheless, the β-structure content is about the same in both of these states. A temperature-induced noncooperative melting process takes place from 10 to 67°C with a decrease of the antiparallel β-form content by about one third. The remaining part of the β-form melts with a more intensive heat absorption, with a maximum at 87°C. The whole melting process is practically reversible. We assume that the observed noncooperative process displays a general property of a new type of structural state of the globular protein - the “molten globule state.”
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360241005
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  • 7
    Electronic Resource
    Electronic Resource
    Determination of stability of the DNA double helix in an aqueous medium (1969)
    New York : Wiley-Blackwell
    Biopolymers 8 (1969), S. 559-571 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The possibility of determining the free energy of stabilization ΔG0 of native DNA structure with the help of calorimetric data on heats ΔH of transition from the native to denaturated state is considered. Results of microcalorimetric measurements of heats of denaturation of T2 phage DNA at, different values of pH and ionic strength of solution are given. Values of free energy of stabilization of the DNA native structure ΔG0 under various conditions have been obtained. It is shown that under conditions close to physiological ΔG0 approaches 1200 cal/mole per base pair.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1969.360080502
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  • 8
    Electronic Resource
    Electronic Resource
    Thermodynamic parameters of helix-coil transition in polypeptide chains I. Poly-(L-glutamic acid) (1971)
    New York : Wiley-Blackwell
    Biopolymers 10 (1971), S. 2161-2179 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The helix-coil transitions for poly(L-glutamic acid) (PGA) in 0.2M NaCl and in its mixture with dioxane were studied by the methods of spectropolarimetry, viscometry, and potentiometric titration at different temperatures from 8 to 50°C. The enthalpy and entropy differences between the helical and coillike states of uncharged PGA molecules were determined from the curves of potentiometric titration. The temperature dependence of the cooperativity parameter σ was determined by two methods: from the sharpness of transition and from the dependence of the intrinsic viscosity on the helical content in the transition region. In 0.2MNaCl, σ= (2.5 ± 0.5) × 10-3 and practically does not depend on temperature, i.e., the cooperativity of the helix-coil transition is connected mainly with the entropy decrease in initiating helical regions (ΔSi ≈ -12 is mole of helical regions). On the contrary, initiation of a helical region in the water-organic solvent mixture is accompanied by a considerable enthalpy increase.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360101111
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  • 9
    Electronic Resource
    Electronic Resource
    A study of apo- and holo-forms of horse liver alcohol dehydrogenase in solution by diffuse X-ray scattering (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 1385-1397 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Apo- and holo-forms of horse liver alcohol dehydrogenase (LADH) in solution were studied by diffuse x-ray scattering. Experimental scattering curves for apo- and holo-forms coincide both with the curves calculated from the crystal structures of apo- and holo-enzymes, and with each other. Thus the “sliding” of catalytical domains in LADH upon substrate binding, which has been shown by x-ray analysis, cannot be detected by diffuse x-ray scattering. Sensitivity of the scattering curves to the domain displacements of sliding and “locking” types has been investigated. It has been shown that the scattering curves of LADH are rather sensitive to the domain “unlocking.” However, these curves change only slightly upon sliding of domains, including the sliding of domains observed in LADH by x-ray analysis.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360250803
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  • 10
    Electronic Resource
    Electronic Resource
    Dipole-dipole interaction and the β structure of synthetic polypeptides (1967)
    New York : Wiley-Blackwell
    Biopolymers 5 (1967), S. 785-787 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1967.360050811
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